Lecture 9 - Integumentary System Flashcards
membranes are composed of:
epithelium (epidermis), and connective tissues (dermis)
what are the 5 major components of the integumentary system (includes skin and accessory structures)
- epidermis (skin)
- dermis (skin)
- exocrine glands (accessory)
- hair (accessory)
- nails (accessory)
- largest organ system of the body (15% of total body mass)
- ranges in thickness
- most accessible system = best indicator of general health
- responds directly to local influences
these are all characteristics of:
skin
what are the five major functions of skin?
1) acts as a barrier: physical and immunological protection
2) thermoregulation
3) sensation: touch, pressure, vibration, temperature, pain
4) metabolic functions
5) social functions
what are the five layers of the epidermis?
- stratum corneum
- stratum lucidum
- stratum granulosum
- stratum spinosum
- stratum basale (germinativum)
(Come Lets Get Sun Burnt)
what is the basal layer of the epidermis?
the stratum germinativum
where are merkel cells and melanocytes found?
stratum germinivatum
stem cells in the stratum germinivatum constantly divide to give rise to new ______ to replace the dead ones that flake off
keratinocytes
the most abundant epithelial cells in the epidermis and synthesize keratin
keratinocytes
forms the basal lamina and ensures that the epithelium is firmly attached to the dermis
stratum germinativum
the least common cell type, but more abundant where skin has no hair
merkel (tactile) cells
what is the function of Merkel cells?
play an important role in touch sensation
what is the tactile (merkel) disc?
dermal sensory nerve fibre
makes up ~8% of epithelial cells - synthesizes melanin pigment
melanocytes
melanin granules are _____ by keratinocytes - form an “umbrella” over the nucleus to _____
phagocytized, protect DNA from UV radiation
what determines skin tone?
activity of granules produced and how they spread out in keratinocytes
what do melanocytes look like?
cells with long, slender processes
composed of several layers (8-10) of daughter living keratinocytes and Langerhans cells with protein filaments that attach keratinocytes together
stratum spinosum
what gives the stratum spinosum its spiny appearance?
adjecent cell junctions (provides strength)
a type of macrophage that originate from bone marrow and migrates to the epidermis
Langerhans (dendritic) cells
what is the role of Langerhan cells?
phagocytic capabilities and play and important role for immune response if pathogens penetrated the superficial layer
where are Langerhan cells found?
found in the oral cavity, esophagus, anal cavity, and vaginal canal
3-5 layers of mature keratinocytes which produce two types of granules, and is associated with a change in cell shape
stratum granulosum
what are kerahyalin granules?
granules produced by keratinocytes in the stratum granulosum which surrounds keratin (important for cornification)
what are lamellar granules?
water-resistant glycolipids produced by keratinocytes in the stratum granulosum which stick cells together (waterproofs the skin)
the accumulation of keratin from deep to superficial layers as cells mature
keratinization
at what layer in the epidermis do cells start to die?
stratum granulosum
how are calluses formed?
the accumulation of too many granules in the stratum granulosum due to abrasion
layer of the epidermis which is only present in volar/hairless skin (palmer and plantar skin)
stratum lucidum
the stratum lucidum has lots of ____ and thickened _____
keratin, plasma membranes
true or false: cells in the stratum lucidum retain their nucleus and organelles
false
contains multiple (20-30) layers of flattened, dead, interlocking keratinocytes which have no more organelles and are fully keratinized
stratum corneum
the most superficial layer of the epidermis
stratum corneum
what is dandruff?
clumps of dander stuck together with oil (sebum) from the scalp
what is the function of the stratum corneum?
protection against abrasion and microbial invasion
how long does it take epidermal cells to go from the stratum basale to the stratum corneum?
30-40 days
the interface between the dermis and epidermis
dermal papilla (dermis) and epidermal ridge (epidermis)
the peak and valley interface between the dermis and epidermis allows for:
a tight bond between the different layers of skin (resists shearing stresses)
in sensitive areas, such as the lips and genitials, the dermal papillae are tall, allowing ____ near the surface
nerve fibres and capillaries
the interface between the dermis and epidermis is very developed and unique to each individual in the:
fingertips
what are dermal papillae made of?
areolar connective tissue containing nerve endings, and many capillaries
what type of tissue is found in the reticular layer of the dermis?
dense irregular connective tissue
provides extensibility and elasticity to the skin, found in the reticular layer of the dermis
collagen bundles and elastic fibres
skeletal muscles of the face attach here for facial expressions
reticular layer of the dermis